Electronic Alarms and Home Security Devices - Leak sensor system design

I have a 8'X14' "well house" that contains my well (submersible pump), tank, water softener, filter, pressure regulator, sprinkler system backflow preventer, etc. In other words, lots of things that could go wrong and cause a leak/flood. I want to set up a leak sensor system that will shut off the power to my pump if it detects a leak, as that is the only single way to make sure I won't have major damage due to a really bad leak.

I've seen the "George Risk leak sensors" and that looks like a good place to start. My preference would be to use two or three of them in different locations in the well house to be able to better detect a leak and to provide redundancy.

The well pump is 1.5hp, 220VAC (about 10 amps when running).

I have used the "relay in a box" from Functional Devices and like them.

I want the system to fail safe, i.e., if I lose power to the sensor or any components in the system, I want the pump to be shut off.

The design should also include a manual override that will allow me to disable the leak sensor system so that I can run the pump even if there is a leak (real or "imagined").

Most of the controls, relays, etc. will be in my shop which is 10' away. That is also where the breaker for the pump is located.

Last requirement (I hope), is that once the sensor detects a leak and shuts off power to the pump, only a manual "reset" can get power back to the pump.

So, any design suggestions? Can all of this be done with off the shelf components?

Thanks,
Ira

Oh yeah, you can do that with off the shelf components.

Really, you don't really need an _alarm_ system for this, this can all be done with relays. The only advantage an alarm system would give is the ability to notify you.

Oh yeah, you can do that with off the shelf components.

Really, you don't really need an _alarm_ system for this, this can all be done with relays. The only advantage an alarm system would give is the ability to notify you.

I already have a way to notify me if this happens. I think I have it figured out. The only component I can't find (don't know what it is called) is something that once a leak is detected will keep power off at the pump, even if the leak dries up.

I can use a normally closed "G. Risk leak sensor" and a 24vdc wall wart to detect the leak. I can use a Functional Devices NO DPST "relay in a box" to control power to the pump on the contacts side based on the presence (or lack thereof) of 24vdc on the coil side. The relay also has a built-in double pole override switch so I can override the leak sensor if I want to.

So, when there is no leak, the 24vdc from the wall wart goes thru the NC leak sensor to the NO relay coil keeping the contacts closed and power available to the pump. When a leak is detected, the leak sensor contacts open so the 24vdc doesn't make it to the relay coil, so the relay contacts open denying power to the pump.

But, once a leak happens and then dries up (maybe without me knowing about it), how do I keep the 24vdc away from the relay coil so the pump will remain off until I fix the leak and "reset" everything? I don't want the pump to come back on resulting in a leak being detected again and starting the cycle over again.

Thanks,
Ira

The simplest way is to use a relay with 2 independent sets of contacts. The normal operating condition has this relay powered with one set of contacts maintaining power to the well pump contactor. The second contact maintains power to the relay coil itself; with a momentary N/O switch in parallel to the second set of contacts.

Your water detection system breaks power to the dual relay, and the only way to restore the relay is for both the water detection to be normal, _and_ someone has to manually push the momentary switch.

I hope it makes sense. I can sketch out the diagram, but it sounds like you have a pretty good electrical grasp.

Ron,

You may be giving me more credit than I deserve on the electrical knowledge. ;)

In case it helps, this (http://www.functionaldevices.com/pdf/RIB24S2.pdf) is the self-contained relay I plan on using to control power to the well pump. This (http://www.grisk.com/specialty/2600water_sensor.htm) is the leak sensor I plan to use.

I've been doing a lot of google'ing trying to find info on what you suggest, but I guess I'm not using the right keywords. I tried "dual relay", "independent contacts relay", "flip flop relay" and others and never found anything that made sense.

So, first question...does the relay you suggest replace the one I linked to, or does it go "in between" the leak sensor and the relay that controls the pump?

Second question...can you point me to a web site that has the device you are talking about, or give me something to search on?

I do pretty good at figuring out how things go together once I have found all the right components and have diagrams of how they work.

Thanks again,
Ira

Ok, lets see if this works:

http://i627.photobucket.com/albums/tt355/MrRonFL/flood_diagram.jpg

I based this quickie diagram on the components you posted.

(10 minutes to draw, 30 minutes to figure out how to post it....)

Ok, lets see if this works:

http://i627.photobucket.com/albums/tt355/MrRonFL/flood_diagram.jpg

I based this quickie diagram on the components you posted.

(10 minutes to draw, 30 minutes to figure out how to post it....)

I wouldn't have thought of that in a million years. Let me make sure I understand...the same kind of relay I planned to use to finally control 220vac to the pump itself (i.e., what you called the motor contactor coil), is also used, along with the momentary switch, to provide the "magic piece" between the leak sensor and the pump control relay. Is that correct? Your diagram explains it well.

I guess I should also plan on having the DC control voltages under the protection of a UPS, since a momentary loss of power to the wall wart would cause the contacts on the "control relay" to open and ultimately shut off power to the pump until the control relay is reset. I should probably consider options using different versions of the sensor and relays (i.e., NO instead of NC in some places) to see if that makes more sense given the various scenarios and their likelihood of occuring.

Thanks for your help.

Regards,
Ira